STERILIZATION OF DENTAL INSTRUMENTS

¹ Department of Oral Pathology, School of Dental and Oral Surgery, Columbia University, New York City

Some of the more common methods of sterilization with chemicals and with heat have been discussed. The factors upon which successful sterilization are dependent have been emphasized. The conclusions that may be drawn from the data presented are these:

1. Successful use of various germicides is dependent upon such factors as (a) presence of organic matter, (b) period of exposure, (c) temperature, (d) dilution of germicide, (e) condition of organisms (moist or dry), and (f) spore formation.

2. Mercuric chloride is unsatisfactory for instrument sterilization owing to its corrosive action and poor germicidal activity in the presence of organic matter, such as blood, pus, and saliva.

3. Lysol and tricresol are three times as germicidal as phenol, and unlike phenol are promptly destructive of spores. Their aqueous solutions do not corrode instruments, even after immersion for several days.

4. Formaldehyde gas has not been practical for instrument sterilization since, at ordinary temperatures, insufficient gas is obtained from the watery solutions. The vapors are given off too slowly and in quantities too variable to be germicidal.

5. Formalin solutions should be used in concentrated dilutions (over 5 percent). It is advisable to add potassium soap (2 to 4 percent) to prevent rusting and also to increase germicidal activity.

6. Alcohol should not be used in concentrations higher than 60 to 70 percent. Dry organisms are not attacked as readily as moist organisms. Alcohol is not dependable for the destruction of spores.

7. Alcohol-glycerin mixture is no more germicidal than 70 percent alcohol. Possibly the addition of glycerin reduces its germicidal activity. Dry staphylococci were not destroyed by immersion for thirty minutes in this mixture.

8. Alcohol and the flame cannot be depended upon for the destruction of other than non-spore-formers. In the presence of grease, oil, and blood, the destructive action is questionable.

9. Metaphen-C is satisfactory, since no corrosion occurs and it possesses high germicidal power.

10. Hexylresorcinol ("S.T. 37") possesses high germicidal power. Corrosion of instruments occurs in aqueous solutions unless the instruments are promptly dried.

11. Boiling water containing alkali, such as sodium hydroxide, is the most satisfactory method of assuring successful sterilization. The disadvantages of this method are rusting and dulling of instruments. Rusting may be prevented by carefully drying the instruments daily.

12. An oil bath is an ideal agency for the sterilization of instruments, in which rusting and dulling of instruments are prevented.

13. A steam sterilizer, to be run efficiently, must not be overpacked and must not contain entrapped air.